Fiber Optic Cables Having Coupling and Methods Therefor

ABSTRACT

A fiber optic cable including at least one optical fiber disposed within a cavity of a cable jacket and methods for manufacturing the same are disclosed. The cavity has a first cavity cross-sectional area and a second cavity cross-sectional area located at different longitudinal locations along the cable, where the first cavity cross-sectional area is greater than the second cavity cross-sectional area. The region of the second cavity cross-sectional area of the cable provides and/or increases the coupling level of the at least one optical fiber to the cable jacket. In further embodiments, the fiber optic cable is a dry cable having one or more dry insert within the cavity for cushioning and/or optionally providing water-blocking for the cable.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/888,182,filed Jul. 31, 2007, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present invention relates generally to fiber optic cables andassemblies that are useful for routing optical fibers toward thesubscriber and/or other suitable cables/assemblies in an opticalnetwork. Specifically, the fiber optic cables and assemblies of thepresent invention have one or more features for providing and/ortailoring the level of coupling for the optical fibers, optical fiberribbons, or the like.

BACKGROUND

Communication networks are used to transport a variety of signals suchas voice, video, data transmission, and the like. Traditionalcommunication networks use copper wires in cables for transportinginformation and data. However, copper cables have drawbacks because theyare large, heavy, and can only transmit a relatively limited amount ofdata with a reasonable cable diameter. Consequently, optical waveguidecables replaced most of the copper cables in long-haul communicationnetwork links, thereby providing greater bandwidth capacity forlong-haul links. However, most communication networks still use coppercables for distribution and/or drop links on the subscriber side of thecentral office. In other words, subscribers have a limited amount ofavailable bandwidth due to the constraints of copper cables in thecommunication network. Stated another way, the copper cables are abottleneck that inhibit the subscriber from utilizing the relativelyhigh-bandwidth capacity of the optical fiber long-haul links.

Fiber optic cables used for distribution or drop links should have thenecessary characteristics for the application. For instance, the fiberoptic cable designs should provide water-blocking, cushion the opticalfibers, couple the optical fibers to the buffer tube or cable jacket,and allow movement of the optical fibers during bending, installation,or the like However, not all fiber optic cable designs provided all ofthese characteristics and instead rely on installation procedures toachieve the desired characteristics.

For instance, some fiber optic cable designs can require specialinstallation procedures such as coiling the cable at specified intervalsfor providing coupling to the optical fibers. Using installationprocedures to achieve the desired characteristics can be problematicand/or add complexity and expense. By way of example, the fiber opticcable can be installed improperly and fail to provide the proper levelof coupling. Additionally, the coiling of the cable requires extra cablelength within the optical network. If the fiber optic cable is used as adistribution cable, coiling of the cable can interfere with intendednode locations (e.g., distribution locations) along the length of thecable.

Thus, there has been a long-felt need for fiber optic cable designs thatprovide all of the required performance characteristics along with quickand easy access and deployment without requiring special installationtechniques. Moreover, the reliability and robustness of the fiber opticcables and the interconnection therebetween must withstand the rigors ofan outdoor environment.

SUMMARY

To achieve these and other advantages and in accordance with the purposeof the invention as embodied and broadly described herein, the inventionis directed to fiber optic cables that have one or more features forproviding and/or tailoring the level of coupling for the optical fibers,optical fiber ribbons, or the like and methods for making the same.

One aspect the invention is directed to a fiber optic cable having atleast one optical fiber disposed within a cavity of a cable jacket thatchanges cross-sectional area along its longitudinal length for providingand/or tailoring coupling. Specifically, the cavity has a first cavitycross-sectional area and a second cavity cross-sectional area located atdifferent longitudinal locations along the cable, wherein the firstcavity cross-sectional area is greater than the second cavitycross-sectional area. By way of example, the cavity has a cavitycross-sectional ratio defined as the second cavity cross-sectional areadivided by the first cavity cross-sectional area, where the cavitycross-sectional ratio is between about 50% and about 90%. Inadvantageous embodiments, the fiber optic cables are dry cable designsthat eliminate the thixotropic grease/gel from the cable. Additionally,the present invention is directed to methods for making fiber opticcables where the cross-sectional area of the cavity changes along itlongitudinal length.

Another aspect the invention is directed to a fiber optic cable havingat least one optical fiber and a dry insert disposed within a cavity ofa cable jacket where the dry insert changes thickness along itslongitudinal length for providing and/or tailoring coupling.Specifically, the dry insert has a first thickness at a firstlongitudinal location and a second thickness at a second longitudinallocation where the first thickness is greater for the second thickness,thereby creating a thickness variation along the longitudinal length ofthe at least one dry insert. By way of example, the dry insert has a dryinsert thickness ratio defined as the second thickness divided by thefirst thickness, where the dry insert thickness ratio is between about50% and about 90%. Additionally, the present invention is directed tomethods for making fiber optic cables where the dry insert changesthickness along it longitudinal length.

It is to be understood that both the foregoing general description andthe following detailed description present exemplary and explanatoryembodiments of the invention, and are intended to provide an overview orframework for understanding the nature and character of the invention asit is claimed. The accompanying drawings are included to provide afurther understanding of the invention, and are incorporated into andconstitute a part of this specification. The drawings illustrate variousexemplary embodiments of the invention, and together with thedescription, serve to explain the principles and operations of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the location of cross-sectional planes ofan explanatory fiber optic cable according to the present invention.

FIGS. 2A and 2B depict respective cross-sectional views at thecross-sectional planes of FIG. 1 for an explanatory dry fiber opticcable.

FIGS. 3A-3D depict respective cross-sectional views of explanatory dryinserts for use with the concepts of the present invention.

FIGS. 4A and 4B depict respective cross-sectional views at the sectionalplanes of FIG. 1 for another explanatory dry fiber optic cable accordingto the present invention.

FIGS. 5A and 5B depict respective cross-sectional views at the sectionalplanes of FIG. 1 for still another explanatory dry fiber optic cableaccording to the present invention.

FIGS. 6A and 6B depict respective cross-sectional views at the sectionalplanes of FIG. 1 for a toneable fiber optic cable according to thepresent invention.

FIGS. 7A and 7B depict respective cross-sectional views at the sectionalplanes for a fiber optic cable having armor according to the presentinvention.

FIGS. 8A and 8B depict respective cross-sectional views at the sectionalplanes for a fiber optic cable having armor according to the presentinvention.

FIGS. 9A and 9B depict respective cross-sectional views at the sectionalplanes for a round fiber optic cable according to the present invention.

FIG. 10 is a side view of a generic dry insert having a change inthickness along a longitudinal direction according to the concepts ofthe present invention.

FIGS. 11A and 11B are respective cross-sectional views showing anexplanatory fiber optic cable using the dry insert of FIG. 10 accordingto the present invention.

FIG. 12 schematically depicts an explanatory manufacturing line formaking fiber optic cables according to the present invention.

FIGS. 13A and 13B schematically depicts concepts for changing across-sectional area of the cavity according to the present invention.

FIGS. 14A and 14B schematically depict another method for changing across-sectional area of the cavity according to the present invention.

FIG. 15 depicts a perspective view of a fiber optic cable assembly thatincludes a fiber optic cable along with a tether cable that ispreconnectorized with a hardened connector according to the presentinvention.

FIG. 16 depicts another perspective view of a fiber optic cable assemblythat includes a fiber optic cable along with a tether cable having amultiport according to the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to exemplary embodiments of theinvention, examples of which are described herein and shown in theaccompanying drawings. Whenever practical, the same reference numeralsare used throughout the drawings to refer to the same or similar partsor features. FIG. 1 depicts an explanatory fiber optic cable 10(hereinafter cable 10) according to the present invention that can beconfigured for use as a drop cable, a distribution cable, or othersuitable portions of an optical network. Generally speaking, adistribution cable will have a relatively high optical fiber count suchtwelve or more optical fibers for further distribution to the opticalnetwork. On the other hand, a drop cable will have a relatively lowoptical count such as up to four optical fibers for routing towards asubscriber or a business, but drop cables may include higher fibercounts. As depicted, the portion of cable 10 shown includes an A-regiondisposed between a first B-region and a second B-region along itslongitudinal length as noted by the brackets. Cables of the inventionhave A-regions and B-regions that provide different levels of couplingof the optical fiber to the cable jacket or tube, thereby advantageouslyallowing tailoring of the coupling level for the optical fiber(s).Specifically, the cable design tailors the desired level of coupling byusing a cross-sectional restriction of a cavity for the cablejacket/tube and/or using a cable component such as a dry insert with athickened portion. Moreover, the concepts of the invention may also beadvantageous since the B-region also provides a necked down area and/orcable component filled area where inhibiting the migration of wateralong the cable is easier. Explanatory cross-sectional views of thedifferent regions of explanatory cable 10 are taken at cross-sectionalplanes A-A and B-B as shown by FIG. 1 and represent the respectiveA-region and B-region for each cable.

FIGS. 2 a and 2 b depict respective cable cross-sections for anexplanatory dry cable 10 respectively taken along cross-sectional planesA-A and B-B of FIG. 1. As shown, cable 10 includes at least one opticalfiber (not visible) that is a portion of an optical fiber ribbon 13(represented by the horizontal line), a first dry insert 22, a seconddry insert 23, at least one strength member 24, and a cable jacket 28having a cavity 28 a. Generally speaking, cable 10 shown in FIGS. 2 aand 2 b has a generally flat profile, but other cable designs can haveother profiles such as round or the like. In other words, cable jacket28 has two major surfaces (not numbered) that are generally flat and areconnected by arcuate end surfaces (not numbered) as shown, therebyresulting in a cable having a relatively small cross-sectionalfootprint. Generally speaking, cavity 28 a of cable jacket 28 has agenerally rectangular shape for carrying one or more fiber optic ribbonsin a non-stranded configuration. Simply stated, optical fiber ribbon 13is disposed between first dry insert 22 and second dry insert that havea compressible layer, thereby providing cushioning, coupling, andoptionally water-blocking. As shown, this cable also has strengthmembers 24,24 disposed on opposing sides of cavity 20, thereby impartinga preferential bend characteristic to the cable that is generallyaligned with the preferential bend characteristic of the ribbon. By wayof example, strength members 24,24 are preferably a dielectric materialsuch as glass-reinforced plastic (GRP) having a diameter such as about2.3 millimeters, thereby allowing an all dielectric cable design;however, other strength member material, sizes, and/or shapes arepossible. For instance, strength members can use a conductive materialsuch as steel, copper-clad steel, or the like and/or they may haveshapes other than round such as the oval.

Cavity 28 a is sized for allowing ribbons or optical fibers the adequatefreedom to move when, for instance, the cable is bent while maintainingadequate optical attenuation performance and the B-region has one ormore features that allows the tailoring of the coupling level of opticalfibers to cable jacket 28. More specifically, cavity 28 a has a firstcavity cross-sectional area (CA1) depicted in FIG. 2A and a secondcavity cross-sectional area (CA2) depicted in FIG. 2B, where the firstcavity cross-sectional area (CA1) is greater than the second cavitycross-sectional area (CA2). As shown, the change in cavitycross-sectional areas is generally attributable to a change between afirst cavity height CH1 and a second cavity height CH2 since the cavitywidth (not numbered) remains similar. As represented by FIG. 2B, secondcavity cross-sectional area (CA2) is asymmetrical about the neutralbending axis of the cable, but other configurations could have generallysymmetrical second cavity cross-sectional area about the neutral bendingaxis. The orientation of the second cavity cross-sectional area maydepend on the method for creating the B-region as discussed herein. Byway of example, cavity 28 a can have a cavity cross-sectional ratiodefined as the second cavity cross-sectional area (CA2) divided by thefirst cavity cross-sectional area (CA1) with the cavity cross-sectionalratio (CA2/CA1) being between about 50% and 90%. By way of a numericalillustration, a nominal cavity height for the A-region is 5.5millimeters and a nominal cavity height for the B-region is about 3.7millimeters (with the same cavity width), thereby yielding a cavitycross-sectional ratio of about 67%.

Simply stated, the B-region allows tailoring of the coupling byproviding and/or increasing the compression of the dry inserts 22,23(i.e., the B-region may provide all of the coupling or a substantialfraction thereof). Compression of dry insert(s) is actually a localizedmaximum compression of the dry insert(s) that occurs where the ribbonsundulate into the same due to the excess ribbon length (ERL) of theoptical fiber ribbon 13 (i.e., the ribbons are longer than the cavityfor the length of the cable). In other words, the compression of the dryinserts creates a normal force on the ribbon(s), thereby helpingmaintain the longitudinal position of the optical fibers/ribbons duringnormal cable operating conditions. Further, cable 10 can have aplurality of B-regions disposed along its longitudinal length withpredetermined spacing and/or lengths (i.e., intermittently disposedalong the length of the cable) for the B-region to tailor to a desiredlevel of coupling. For instance, the cable can have a plurality ofB-regions having a longitudinal length of between about 1-10 centimetersdisposed between A-regions having a longitudinal length of between about300-10,000 centimeters, but other suitable region lengths and/orpatterns are possible. Using a relatively short length for the B-regiontends to force a node at that location for the undulating opticalfibers, while still allowing the optical fibers the necessary freedom tomove.

Optical fiber ribbons 13 used in the cables of the present invention canhave any suitable design or ribbon count as known in the art ordeveloped hereafter. For instance, optical fiber ribbons 13 can have anysuitable subunit construction, a common matrix construction, geometry,stress concentrators, different fiber counts, and/or the like. Subunitsallow predetermined splitting of the optical fiber ribbons intopredictable smaller fiber count units, preferably without the use ofspecial tools. By way of example, fiber optic ribbon 13 is a twenty-fourfiber ribbon having two twelve-fiber units each having three subunitswith four optical fibers. Of course, other suitable twenty-four fiberribbon configurations are possible such as two twelve fiber units, threeeight fiber units, four six fiber units, or six four fiber unitsdepending on the requirements of the network architecture.

Optical fibers preferably have an excess fiber length (EFL) comparedwith a length of cavity 28 a; however, in some instances the EFL mayalso be slightly negative. Likewise, ribbons can have an excess ribbonlength (ERL) with respect to the length of the cavity. Besidesinhibiting the application of strain to the optical fibers, EFL or ERLcan aid in coupling the optical fibers or ribbons with the cable jacketor tube. By way of example, the ERL is preferably in the range of about0.1 percent to about 1.2 percent, and more preferably in the range ofabout 0.3 percent to about 1.0 percent, and most preferably in the rangeof about 0.5 percent to about 0.8 percent, thereby inhibiting theapplication of strain, allowing bending of the fiber optic cable withoutcausing elevated levels of optical attenuation, and/or suitable lowtemperature performance. Additionally, the amount of ERL may depend onspecific cable design such as the number of ribbons within the cavity,the cavity size, cavity shape, intended application, and/or otherparameters.

As depicted in FIG. 2B, coupling for optical fiber ribbon 13 is providedin the B-region by the compression of dry inserts 22,23 on optical fiberribbon 13 due to the smaller cavity height CH2. No matter theconstruction and/or materials of the dry insert(s) or the like, thecable design should provide the desired level of coupling for theoptical fibers to the cable jacket or tube. Additionally, in order toquantify the level of coupling for the optical fibers a relatively longlength of cable is required. By way of example, optical fibers of cablesaccording to the present invention have a coupling force of at leastabout 0.1625 Newtons per optical fiber for a thirty-meter length offiber optic cable. Illustratively, a fiber optic cable having a singleribbon with twelve optical fibers in the ribbon should have a minimumcoupling force of about 1.95 Newtons for a thirty-meter length of fiberoptic cable. Likewise, a similar fiber optical cable having a singleoptical fiber ribbon with six optical fibers should have a minimumcoupling force of about 0.975 Newtons for a thirty-meter length of fiberoptic cable. Measurement of the coupling force is accomplished by takinga thirty-meter fiber optic cable sample and pulling on a first end ofthe optical fibers (or fiber optic ribbon(s)) and measuring the forcerequired to cause movement of the second end of the optical fiber(s) (orfiber optic ribbon(s)). In other words, the EFL (or ERL) must bestraightened so that the coupling force is the amount of force requiredto move the entire length of optical fibers within the thirty-meterfiber optic cable sample.

Dry inserts can be any suitable material, materials and/or structuresuch as one or more elongate tapes such as a foam tape disposed withinthe cavity for coupling the ribbons with the cable jacket or tube.Optionally, dry inserts can also include a water-blocking characteristicfor blocking the migration of water along the cable. As depicted inFIGS. 2A and 2B, dry inserts 22,23 are disposed on both the top andbottom of ribbon 13. In other words, the components form a elongatetape/ribbon sandwich with the first elongate tape disposed on a firstplanar side of the ribbon (or ribbon stack) and the second elongate tapebeing disposed on a the second major side of the ribbon (or ribbonstack) within the generally rectangular cavity. Stated another way,planar surface(s) of the ribbon generally faces the planar surface ofthe dry inserts and the planar surface of the same is also generallyaligned with the major dimension of the cavity so that all of the majorplanar surfaces of the components are generally aligned within thegenerally rectangular cavity as depicted. Of course, other embodimentsmay have one or more dry inserts wrapped about the optical fibers ordisposed on one or more sides thereof. In this cable, dry inserts 22,23of FIG. 2A are elongate tapes formed from an open cell foam such as apolyurethane material; however, other suitable foam materials forcoupling and cushioning of the ribbons are possible such aspolyethylene, polypropylene, EVA.

Additionally, one or more dry inserts can include an optionalwater-swellable layer (represented by the solid hatching of the dryinsert and not numbered) for inhibiting the migration of water withinthe cable. For instance, a foam layer and a water-swellable layer arelaminated together, thereby forming a composite elongate tape (i.e., awater-swellable foam tape). In other embodiments, the compressible layerand the optional water-swellable layer are discrete individualcomponents that are unattached (i.e., a separate compressible layer andwater-swellable component such as being a water-swellable yarn orthread). Generally speaking, dry inserts used herein aremulti-functional. For instance, besides aiding the coupling the opticalfibers, ribbons, modules, or the like to the cable jacket, they mayoptionally inhibit the migration of water, as well as cushion theoptical fibers during bending of the cable. Although the dry inserts areshown having a width smaller than the cavity, the dry inserts may have awidth that is greater than the cavity. Additionally, dry inserts canhave other constructions besides an elongate foam tape and the optionalwater-swellable layer can have any suitable material(s)/construction(s).

Illustratively, FIG. 3 a depicts one example of another dry insert 22′.Dry insert 22′ includes a compressible layer formed from a plurality ofmicrospheres 22 b′ disposed between a top tape 22 a′ and bottom tape 22a′. As with other tapes used for the dry insert, tapes 22 a′ can beformed from any suitable material such as a non-woven material, apolyester film like Mylar, or other like materials. More specifically,microspheres 22 b′ are generally disposed between tapes 22 a′ and areattached using a suitable method such as an adhesive, binding agent,application of heat and/or pressure, or the like. Additionally, anoptional water-swellable substance such as a plurality ofwater-swellable particles, a plurality of water-swellable fiber, or awater-swellable coating 22 c′ may also be disposed between tapes 22 a′with microspheres 22 b′ or on a portion one or more tapes 22 a′.Suitable materials for microspheres 22 b′ are relatively soft so theyare compressible and sized so that they will not cause undue levels ofoptical attenuation if they press against the optical fiber or ribbon.By way of example, suitable hollow microspheres are available from AkzoNobel of the Netherlands under the tradename EXPANCEL and includescopolymers of monomers vinylidene chloride, acrylonitrile, andmethylmethacrylate. Other plastic hollow microspheres are available fromAsia Pacific Microspheres of Malaysia under the tradename of PHENOSET,which are phenolic and amino-based micro spheres.

The compressible nature of hollow polymeric microspheres is suited forproviding adequate coupling of the optical fibers to the tube or cablejacket. Additionally, the smooth round surface of these microspherespermits pressing against the optical fibers without inducing elevatedlevels of optical attenuation such as during bending, twisting, orcrushing of the cable. Additionally, the size of the hollow microspherescan vary from about 1 micron to about 300 microns, likewise, a wallthickness of the microspheres can also vary from about 0.1 micron up toseveral microns, but other suitable dimensions are possible as long as asuitable level of optical performance is maintained.

FIG. 3 b depicts another example of a dry insert 22″ that provides acompressible layer 22 b″ using the geometry of its shape. Morespecifically, compressible layer 22 b″ is provided by using adimensional fabric that has a generally textured shape in one or moredirections for providing the compressible layer. As shown, dry insert22″ has a generally textured shape TS and is formed from a suitably softand flexible material so that it can deform for providing an adequatelevel of coupling for the optical fibers or ribbons without causingundue levels of optical attenuation. By way of example, suitable fabricsare available from Freudenberg of Durham, N.C. under the name ofNovolon. The dimensional fabrics may be formed from a variety ofmaterials such as polyester, polypropylene, nylon, or other suitablematerials. Generally speaking, dimensional fabrics are formed using amolding process for transforming a two-dimensional (i.e., flat) fabricor substrate into a three-dimensional (i.e., textured shape) fabric orsubstrate with the desired textured shape TS. The coupling and/orcompressibility of dry insert 22″ can be tailored by changing parameterssuch as the number of contact points per surface area (i.e., changingthe density of high and low contact points), the height from a highpoint to a low point, the dimension fabric profile, and/or flexibilityof the dimensional fabric. Again, dry insert 22″ can include an optionalwater-swellable layer for blocking the migration of water along thecable or tube assembly. For instance, the water-swellable layer may be acoating applied to one or more surfaces or applied to the fibers of thedimensional fabric, include water-swellable particles disposed in or onthe dry insert, and/or may include superabsorbent fibers. Suitablewater-swellable filaments are, for example, LANSEAL materials availablefrom Toyobo of Osaka, Japan or OASIS materials available from TechnicalAbsorbents Ltd. of South Humberside, United Kingdom.

FIG. 3 c depicts a further embodiment of a dry insert 22′″ having acompressible layer 22 b′″ having a non-woven layer of felt substancemade of one or more materials formed from non-continuous and/orcontinuous filaments. Dry insert 22′″ may optionally include awater-swellable layer and/or one or more tapes for attaching the feltsubstance thereto. For instance, dry insert 22′″ includes a plurality ofwater-swellable filaments 22 a′″ along with other filaments 22 b′″ thatare non-swellable disposed between a plurality of optional tapes 22 c′″,thereby forming dry insert 22′″, As used herein, “felt substance” meansa material comprising one or more types of non-continuous or continuousfilaments and/or fibers which have been caused to adhere and/or matttogether through the action of heat, moisture, chemicals, pressure, ormechanical action such as needle-punching or spun-lacing, or acombination of the foregoing actions, thereby forming a relatively thickand compressible layer. Water-swellable filaments 22 a′″ may compriseany suitable water-swellable material. By way of example, dry insert22′″ of FIG. 3 c may include about 25% or less by weight ofwater-swellable filaments 22 a′″ and about 75% or more by weight ofother filaments 22 b′″; however, other suitable ratios are possible.Other filaments 22 b′″ may include any suitable filament and/or fibermaterial such as polymer filaments like polypropylene, polyethylene, andpolyesters, likewise, other suitable materials such as cottons, nylon,rayons, elastomers, fiberglass, aramids, polymers, rubber-basedurethanes, composite materials and/or blends thereof may be included asa portion of other filaments 22 b′″ and may be tailored for providingspecific characteristics.

FIG. 3 d depicts yet another dry insert 22″″ shaped as a generally flattape having a compressible layer with a suitable width. By way ofexample, dry insert 22″″ is made of a plurality of filaments such as aplurality of generally continuous polyester filaments grouped togetherby a matrix material, but the use of other filament materials ispossible. An optional compressible layer is formed by, for instance,foaming the matrix material, thereby providing a compressible layer 22b″″. In other embodiments, the matrix material is not foamed so itdoesn't provide a compressible layer, but still provides the desiredlevel of coupling using friction. Additionally the matrix material isused for attaching a plurality of water-swellable particles to dryinsert 22″″ for forming a water-swellable layer 22 a″″. Suitable foamedmatrix materials include vinyls, polyurethanes, polypropylenes, EVAs, orpolyethylene blends. The plurality of filaments and the matrix materialare run through a die that forms dry insert 22″″ into its desired shapesuch as a generally flat ribbon-like profile. Dry inserts 22″″ may berun parallel to the fiber ribbons in a sandwich configuration or haveother configurations such as helically wrapped about the optical fibersor ribbon stack. Other similar constructions are possible using anysuitable materials for providing the compressible layer and thewater-swellable layer. Dry insert can include still other constructionsand/or materials such as sponge-like materials for a compressible layersuch as polyvinylalcohol (PVA).

Although cavity 28 a is depicted with a generally rectangular shape witha fixed orientation for housing the optical fiber ribbon, other shapesand arrangements are possible such as generally square, round, or oval.By way of example, cavity may be rotated or stranded in any suitablemanner along its longitudinal length. The cavity can also have a partialoscillation through a given angle, for instance, the cavity can rotatebetween a clockwise angle that is less than a full rotation and thenrotate counter-clockwise for less than a full rotation. Furthermore, oneor more cavities may be offset towards one of the major surfaces,thereby allowing easy opening and access from one side. The cavity of amanufactured cable may have a slightly distorted (i.e., rounded ordeformed) cross-section since it is difficult to maintain the sharpedges during manufacturing.

Cables according to the present invention may have any suitabledimensions, constructions, and/or fiber counts for the givenapplication. By way of example, in distribution applications the widthof the cable is preferably about 20 millimeters or less and the heightof the cable is preferably about 12 millimeters or less. In dropapplications, the width of the cable is preferably about 10 millimetersor less and the height of the cable is preferably about 5 millimeters orless. Of course, other cables of the present invention can have othersizes and/or structures for the given application depending on therequirements and fiber count of the cable. For instance, cables of thepresent invention may have larger dimensions for the major dimension,the minor dimension, and/or different structures such as a toneableportion as shown in FIGS. 6A and 6B for locating the cable in buriedapplications. Likewise, cable jackets and/or other cable components maybe formed from a flame-retardant material and/or the cable can have aflame-retardant characteristic, thereby making it suitable for indoorapplications such as multi-dwelling units (MDUs) or the like.

Besides being a dry cable design, the cable of FIGS. 2A and 2B is alsoadvantageous because it can be easily accessed from either of thegenerally planar sides of the cable, thereby allowing access to thedesired optical fiber. In other words, ribbons from either side of theribbon stack, i.e., top or bottom, can be accessed by opening the cableat the respective planar side. Consequently, the craftsman or automationprocess has simple and easy access to the cavity 28 a by running autility blade or cutting tool along the length of the cable withoutcutting into strength members, thereby allowing entry to cavity whileinhibiting damage to the optical fibers and/or strength members duringthe access procedure. In other words, the craftsman can simply cut intocable jacket by slicing the cable jacket and may use strength members asa guide for the blade or cutting tool, thereby exposing cavity duringthe cutting and allowing access to the at least one optical fibertherein. Thus, the optical fibers in the cables of the present inventionmay be easily, quickly, and repeatably accessed by a craftsman orlikewise in an automated process. Additionally, the generally flat majorsurfaces of the cables are advantageous because they allow for a smallercable footprint and uses less jacket material compared with roundcables. Although the cable depicted in FIGS. 2A and 2B is a generallyflat dry cable design having the fiber optic ribbon disposed between twodry inserts having a foam tape with a laminated water-swellable tape,the concepts of the invention are possible with other cableconfigurations.

FIGS. 4A and 4B depict another cable 10 that is similar to the cable ofFIGS. 2A and 2B, but only includes a single dry insert 42 within cavity28 a of cable jacket 28. As shown, in FIG. 4A, dry insert 42 and opticalfiber ribbon 13 are, generally speaking loosely disposed within cavity28 a within the A-region, thus there is little to no coupling providedby this region (i.e., there is a vertical free space within the cavity).On the other hand, the B-region depicted by FIG. 4B provides thecoupling since dry insert 42 is compressed within cavity 28 a forproviding a predetermined level of coupling. Dry insert can becompressed within the cavity to provide coupling using one or moremethods. For instance, one method for compressing the dry insert 42 isby reducing the height of cavity 28 a, thereby providing the desireddegree of coupling. Dry insert 42 provides another method for providingcoupling by using a thickness variation along the longitudinal length ofdry insert 42. For instance, FIG. 10 is a side view of dry insert 42showing a thickness that varies along its longitudinal length. Simplystated, dry insert 42 has a portion with a first thickness T1 and aportion with a second thickness T2 where the first thickness T1 isgreater than the second thickness T2. The portion of dry insert 42 thathas first thickness T1 forms a portion of the B-region of the cablesince the dry insert thickness is compressed when disposed within thecavity 48 a with the optical fiber ribbon 13. By way of example, dryinsert 42 can have a dry insert thickness ratio defined as the secondthickness T2 divided by the first thickness T1 with the dry insertthickness ratio (T2/T1) being between about 50% and 90%. By way of anumerical illustration, a nominal first thickness for the A-region ofdry insert 42 is about 3.5 millimeters and a nominal second thicknessfor the B-region of dry insert 42 is about 4.5 millimeters, therebyyielding a dry insert thickness ratio of about 77%. Moreover, thethickened portion of dry insert 42 can have any suitable length and/orperiod along the length of same. Also, like dry insert 22, dry insert 42can be formed from any suitable material, construction, or the like.

FIGS. 5A and 5B depict another cable that is similar to the cable ofFIGS. 2A and 2B, but it depicts a plurality of dry inserts 22′ disposedwithin a cavity 28 a of cable jacket 28 along with a toneable lobe 58 bthat is useful for locating the cable in buried applications while stillallowing for a dielectric main cable body 58 a. As shown, the cable hasfour dry inserts 22′ disposed within cavity 28 a to cushion, couple andprovide water-blocking. Specifically, dry inserts 22′ are generallydisposed to sandwich optical fiber ribbon therebetween, but the dryinserts 22′ may migrate within cavity 28 a to other positions. FIG. 5Bshows a cross-sectional view of cavity 58 a being constricted at theB-region. Additionally, other suitable inserts may be used with thiscable or any other cable.

Toneable lobe 58 b includes a conductive wire 55 disposed withintoneable lobe 58 b. By way of example, conductive wire 55 is a 24-gaugecopper wire that allows the craftsman to apply a toning signal theretofor locating the cable so it can be located or have its location markedto prevent inadvertent damage. A cable jacket 58 and jacket portion oftoneable lobe 58 b are typically co-extruded simultaneously using thesame extrusion tooling. As shown, toneable lobe 58 b is connected withcable jacket 58 of the main cable body 58 a by a frangible web (notnumbered) so that toneable lobe 58 b can easily be separated from maincable body 58 a for connectorization or other purposes. Specifically,the web of toneable lobe 58 b can include a preferential tear portion(not visible) using suitable geometry for controlling the location ofthe tear between the toneable lobe 58 b and the main cable body 58 a.Toneable lobe 58 b preferably tears away from the main cable bodycleanly so that it does not leave a ridge thereon, thereby allowing fora profile that permits easy sealing with a connector boot or the like.Using toneable lobe 58 a is advantageous because if the cable is struckby lightning the toneable lobe 58 a would be damaged, but the main cablebody 58 a would not be significantly damaged since it is dielectric.Consequently, the cable is toneable without requiring the labor andhardware necessary for grounding the cable. Of course, other cables ofthe present invention may also include a toneable lobe.

FIGS. 6A and 6B depict another cable 10 that is similar to the cable ofFIGS. 2A and 2B, but it uses a slightly different jacket shape toimprove side crush performance. Additionally, the dry inserts 22,23 ofthis embodiment do not include a water-swellable characteristic, butinstead the cable includes a small quantity of water-swellable powder(not visible) disposed within a cavity 28 a for inhibiting the migrationof water therein. This cable provides improved side crush performancesince cable jacket 28 has an upper concave wall (not numbered) and alower concave wall (not numbered) for improving side-crush strength forthe cable. Concave walls mean that the wall has an outer surface that isgenerally concave with a generally uniform wall thickness (i.e., theinner surface of the wall is curved to match the outer surface.) Inother words, the concave walls increase the cables resistance toside-crush loads and helps preserves optical performance during thesame. Other cables of the present invention may also use this concept.

FIGS. 7A and 7B depict another cable 10 that is similar to the cable ofFIGS. 2A and 2B, but it further includes an armor layer 77 disposedbetween a cable jacket 28 and a second jacket 79. Armor layer 77provides rodent protection and/or additional crush strength for thecable. Specifically, the cable includes an optical fiber ribbon 13disposed within a cavity 28 a of cable jacket 28. Strength members 24are attached to cable jacket 28 and disposed on opposite side of cavity28 a. Armor layer 77 is disposed about cable jacket 28 and is shown witha butting seam, but it may have an overlapping seam. Thereafter, secondjacket 79 is applied over armor layer 77. Armor layer 77 may be formedfrom any suitable material such as a dielectric such as a high-strengthpolymer or a conductive material such as a steel tape. Moreover, thearmor layer may be, shaped, ribbed, corrugated or the like for improvingits crush strength and/or flexural performance of the cable. In otherembodiments, the cable has two armor layers with one armor layer abovethe cavity and one armor layer below the cavity within a single cablejacket. Additionally, the two armor layers within the cable jacket mayhave respective curved end portions that generally contact each strengthmember 24 so that any crush forces are directed and/or transferredtowards the same. Additionally, if a conductive armor component is used,strength members 24 are preferably also formed from a conductivematerial such as steel, rather than a more expensive glass-reinforcedplastic strength member. Moreover, it is also possible to join or attachstrength member 24 with the armor layer 77 by gluing, crimping, welding,or the like. Consequently, the properties of each cable jacket may betailored for performance such as coupling, tear resistance, or the otherproperties. By way of example, cable jacket 28 may be a linearlow-density polyethylene (LLDPE) for tear resistance and outer jacket 78may be a medium or high density polyethylene for durability and abrasionresistance; however, other suitable materials may be used. In thisembodiment, the cavity does not include a tube therein and the minorcavity dimension is smaller than the strength member dimension.Additionally, the cable may include one or more optional ripcords (notvisible) for opening the cable and/or removing the armor layer.

FIGS. 8A and 8B depict still another cable 10 that is similar to thecable of FIGS. 2A and 2B, but includes a plurality of cavities 88 a,88 bfor housing communication elements such as optical fibers and/or copperwires. Using more than one cavity allows for flexibility in the cableapplications. Multiple cavities can have similar or different sizes thatare suited for the particular application. As shown, cavities 88 a,88 bhave similar height dimensions, but have different widths dimensions,thereby allowing different ribbon fiber counts in respective cavitiesand/or other components. Specifically, cavity 88 a is sized for aplurality of fiber optic ribbons 13 that can be accessed fordistribution or the like along the cable and cavity 88 b is sized for aplurality of copper conductors 82. Other embodiments are possible, forinstance, the first cavity can have optical fiber ribbons with 4-fibersand the second cavity can have optical fiber ribbons with 12-fibers.FIGS. 8A and 8B also illustrates an optional strength member 24 disposedbetween cavities 88 a and 88 b. The optional strength member isadvantageous if it desired to only access one of the cavities whenopening the cable by allowing a stopping point and/or a guide for thecutting tool. The optional strength member may be the same size as theoutboard strength members or it may have a different size. Moreover, theoptional strength member may have a shape other than round so that themajor cable dimension may be minimized. Other structures may be used foraiding in opening only one of multiple cavities. For instance, one ormore cavities may be offset relative to the neutral axis that passesthrough the center points of strength members 24. By way of example, thecavity having the four fiber ribbons is easily accessible from one majorsurface and the cavity having the twelve fiber ribbons is easilyaccessible from the other major surface. Moreover, one or more of themajor surfaces may be marked (not visible) to indicate which cavity isaccessible from the given surface. Of course, other cablesconfigurations of the present invention can also use more than onecavity.

FIGS. 9A and 9B depict still another cable 10 configured as a roundcable that includes loose optical fibers 12 and a plurality of dryinserts 22 disposed within a tube 92. In this cable tube 92 has an innerdiameter that changes from the A-region to the B-region. Specifically,the A-region tube 92 has an inner diameter ID1 that is changes to aninner diameter ID2 in the B-region, thereby creating and/or increasingthe coupling of optical fibers 12. In other words, a cavity 98 a changesfrom a first cavity cross-sectional area CA1 to a second cavitycross-sectional area CA2, where the cavity cross-sectional ratio isbetween about 50% and 90%. Although shown as a plurality of dry insertsother embodiments can use a single dry insert that is generally disposedabout the optical fibers. Additionally, this cable includes a pluralityof strength members 92 that are configured as tensile yarns disposedabout tube 92 and a cable jacket 98 therearound.

Besides ribbons and loose optical fibers, other packaging arrangementsfor the optical fibers are also possible such as having a plurality ofoptical fiber modules (not shown). Optical fiber modules organize andprotect the plurality of optical fibers 12 within each module jacketthat is extremely thin, flexible, and easily tearable without tools.Consequently, optical fiber modules can be routed out of the cavity ofthe cable while still having a protective covering disposed about theoptical fibers. By way of example, the optical fiber module includestwelve colored optical fibers 12, thereby forming a relatively highoptical fiber packing density. Moreover, optical fiber module allowsaccess to individual optical fibers within the module jacket withouthaving to remove the same from a ribbon matrix material. Preferably,module jackets are formed from a material that is easily tearablewithout tools. For instance, the module jacket is formed from a highlyfilled material so that it is easily tearable by the craftsman merelyusing his fingers to tear the same and it will not stick to colored ortight-buffered optical fibers during manufacturing. Suitable modulejacket materials may include a polybutylene terephthalate (PBT), apolycarbonate and/or a polyethylene (PE) material and/or an ethylenevinyl acrylate (EVA) or other blends thereof having fillers like a chalkor talc; however, other suitable materials are possible such as aUV-curable acrylate. Modules may include other suitable cable componentstherein such as a grease, water-swellable yarn, suitable thread or tape,a ripcord, or other suitable component. Additionally, the cavity ofcable may include grease, water-swellable yarn or tape, dry insert,and/or any other suitable component as desired.

The concepts of the present invention may also be implemented usingcable having cavities that do not change cross-sectional areas. FIG. 10depicts a side view of a generic dry insert 42 that changes thicknessalong its longitudinal length of the same. Although dry insert 42 isdepicted as having a compressible layer 42 a and a water-swellable layer42 b that are laminated together such as a foam layer and awater-swellable layer the concept is applicable to other suitable dryinserts. Specifically, dry insert 42 has a first thickness T1 that isgreater than a second thickness T2. For instance, a dry insert thicknessratio is defined as the second thickness T2 divided by the firstthickness T1. The dry insert thickness ratio (T2/T1) is between about50% and about 90%, but other values are possible. FIGS. 11A and 11Bdepict another fiber optic cable 10 where a cavity 118 a has a similarcavity cross-sectional area CA1 (likewise the cavity height CH1 is thesimilar) in both the A-region and the B-region. Dry insert 42 can beformed with the first thickness T1 or an additional portion may be addedto a dry insert having a uniform thickness (as represented by theportion above the dashed line), thereby forming the first thickness T1.In other words, an additional portion of a compressible layer may bepositioned and/or attached to the dry insert having a generally uniformthickness at the desired position/spacing, thereby creating dry insert42. As shown by FIG. 11A, optical fiber ribbons 13 are loosely disposedwithin a cavity 118 a of a cable jacket 118 where dry insert(s) 42 has asecond thickness T2. On the other hand, optical fiber ribbons 13 arecoupled within cavity 118 a of cable jacket 118 where dry insert(s) 42have a first thickness T1. The concepts of this cable design may beapplied to other cable designs with or without changing the cavitycross-sectional area.

FIG. 12 schematically illustrates an explanatory one-pass manufacturingline 120 for tubeless fiber optic cables according to the presentinvention such as shown in FIGS. 2A and 2B; however, other variations ofthe concepts may be used to manufacture other assemblies and/or cablesaccording to the concepts of the present invention. One passmanufacturing line 120 includes at least one optical ribbon payoff reel121, a plurality of dry insert payoff reels 122, a plurality of strengthmember payoff reels 123, a plurality of strength member capstans 124, across-head extruder 125, a water trough 126, one or more caterpullers127, and a take-up reel 129. Additionally, tubeless fiber optic cablesmay further include an armor layer and a second cable jackettherearound, thereby forming a tubeless fiber optic cable similar thecable illustrated in FIGS. 7A and 7B. The armor layer and/or secondcable jacket can be manufactured on the same line or on a secondmanufacturing line.

The explanatory manufacturing process includes paying-off at least oneoptical fiber ribbon 13 and dry inserts 22,23 from respective reels 131,132, and 132 and the different methods for forming the coupling featuresare discussed below. Only one payoff reel for optical fiber ribbon 13 isshown for clarity. However, manufacturing lines can include any suitablenumber of payoff reels for one or more ribbons or optical fibers inorder to manufacture assemblies and/or cables according to the presentinvention. Thereafter, dry inserts 22,23 are generally positioned aboutoptical fiber ribbon 13, thereby forming a cable core 21 (i.e., a dryinsert-ribbon composite stack or sandwich). Additionally, strengthmembers 24 are paying-off respective reels 123 under a relatively hightension (e.g., between about 100 to about 600 pounds) using respectivestrength member capstans 124, thereby elastically stretching strengthmembers 24 (represented by the arrows) so that ERL is produced in thetubeless fiber optic cable. In other words, after the tension isreleased on strength members 24 they return to their original unstressedlength (i.e. shorten), thereby producing ERL such as up to 1.2% or moresince the ribbons were introduced into the cable with about the samelength as tensioned strength members and the ribbons were not stretched.Stated another way, the amount of ERL produced is equal to about thestrength member strain (i.e., elastically stretching of the strengthmember) plus any plastic shrinkage of the cable jacket that may occur.The strength member strain can create a significant amount of ERL or EFLin a one-pass production such as 10% or more, 25% or more, 50% or more,and even up to 80% or more of the total ERL or EFL within the cable.Furthermore, elastically stretching of the strength member isadvantageous since it allows for a precise control of the amount of ERLor EFL being introduced into the cable and greatly reduces strengthmember pistoning since the finished cable jacket is in compressioninstead of tension. For the manufacture of the tubeless fiber opticcable 10 of FIGS. 2A and 2B, about 95% of ERL is introduced into thecable by elastically stretching the strength members. Thereafter, cablecore 21 and strength members 24 are fed into cross-head extruder 125where cable jacket 28 is extruded about cable core 21 and strengthmembers 24, thereby forming the tubeless fiber optic cable 10. As shownby FIG. 12, cable jacket is being applied about the optical fibers andstrength members by cross-head extruder 125 while the strength membersare elastically stretched. After extrusion, cable 10 is then quenched inwater trough 126 while the strength member is still elasticallystretched, thereby allowing the cable jacket to “freeze” on thestretched strength members. Tubeless fiber optic cable 10 is pulledthrough the manufacturing line using one or more caterpullers 127 andthen wound onto take-up reel 129 under low tension (i.e., the tensileforce that elastically stretched the strength members is released andstrength members return to a relaxed length thereby creating ERL or EFLin the cable). As depicted in the box, one manufacturing line may beused to form a tubeless fiber optic cable similar to tubeless fiberoptic cable 10 as shown in FIGS. 7A and 7B. As shown, a secondcaterpuller 127 is used for pulling the cable assembly as the armorlayer 77 is paid-off a reel 131 and formed about cable 10 using suitablearmor forming equipment (not depicted), and a second cable jacket 79 isextruded thereover using a cross-head extruder 132. Thereafter, thetubeless fiber optic cable armored cable passes into a second watertrough 134 before being wound-up on take-up reel 129. Additionally,other cables and/or manufacturing lines according to the concepts of thepresent invention are possible. For instance, cables and/ormanufacturing lines may include a water-swellable tape, yarn, or thelike; however, the use of one or more other suitable cable components ispossible.

If the coupling feature is formed merely by using dry insert 42 with achanging thickness then the explanatory manufacturing line shown in FIG.12 is suitable for making the fiber optic cable of FIGS. 11A and 11B.However, if the coupling feature is provided by changing the cavitycross-sectional area then additional manufacturing complexity isrequired for the explanatory manufacturing line of FIG. 12 as discussedbelow. FIGS. 13A and 13B schematically depict one method using anexemplary extrusion tooling 200 for changing the cavity cross-sectionalarea by changing the amount of polymer provided during extrusion of theB-region of the cable. Specifically, extrusion tooling 200 includes atip 202 and a die 204 that can allow more polymer into the cablecross-section, thereby resulting in a smaller cavity cross-section. Morespecifically, during manufacturing one or more portions of die 204 canmove from a first position shown in FIG. 13A to a second position shownin FIG. 13B, thereby allowing more of a molten polymer 208 to pass intothe cable cross-section. Additionally, the extruder screw speed may haveto increase to deliver more molten polymer for the cable jacket. Asshown in FIG. 13B, an upper portion 204 a of die 204 moves upward toallow more molten polymer to flow and creating a thicker jacket wallthickness (i.e., a smaller cavity) in the B-region of the cable. Sinceonly the upper portion 204 a of die 204 moves the cavity formed isasymmetrical, if both an upper and lower portion of die 204 moves thenthe cavity more symmetrical. FIGS. 14A and 14B depict another method forchanging the cross-sectional shape of the cavity. As shown, FIG. 14Ashows the extrusion tooling 200 and a deforming element 206 for makingcable in the A-region. When the B-region of the cable is desired,deforming element 206 contacts the molten cable jacket 208 to deform thesame, thereby changing the cavity cross-sectional area. Othermanufacturing methods are also possible. By way of example, anothermethod may use both a moveable die to increase amount of molten materialand then use one or more deforming elements to create a change incross-sectional shape. Further these methods can be applied to tubesand/or round cable in order to create the desired level of coupling.

Cables of the present invention are also useful as a portion of a largercable assembly that is useful for distributing optical fibers toward thesubscriber. The cable assemblies can be assembled in the factory or theycan be constructed in the field. A variety of fiber optic assemblies maybe constructed from fiber optic cables of the present invention. Forinstance, FIG. 15 depicts fiber optic cable assembly 110 that includesfiber optic cable 10 as a portion of a distribution cable assembly. Asshown, a tether cable 140 is attached to fiber optic cable 10 at a firstend and includes a protective covering 111 for covering the spliceportion between fiber optic cable 10 and tether cable 140. A second endof tether cable 140 can include one or more ferrules attached theretoand the ferrule may be a portion of a receptacle, plug, or the like forplug and play connectivity. Illustratively, FIG. 15 depicts a hardenedplug connector 145 on the second end of tether cable 140. Of course, thesecond end of tether cable 140 can have any suitable configuration forconnectivity such as splice-ready optical fibers, a connector or areceptacle having a ferrule, a multi-port or the like, thereby allowingthe craft flexibility for downstream connectivity. FIG. 16 depicts afiber optic cable assembly 110′ similar to FIG. 15 but it includes amulti-port 160 having a plurality of receptacles 160 a attached to asecond end of tether cable 140. Likewise, other types and/or structuresare possible for fiber optic assemblies according to the concepts of theinvention. For instance, a hardened connector or receptacle could bedirectly attached to the tubeless fiber optic cable.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the cable and cableassemblies of the present invention without departing from the spirit orscope of the invention. For instance, cables or assemblies of thepresent invention can include other cable components such as ripcords,paper or mica tapes, a friction element, and/or other suitablecomponents. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1. A fiber optic cable comprising: at least one optical fiber; and apolymer cable jacket extruded about the at least one optical fiber, thecable jacket having at least one cavity, wherein the at least oneoptical fiber is disposed within the at least one cavity, the at leastone cavity has a plurality of first regions having a first cavitycross-sectional area (CA1) and a plurality of second regions having asecond cavity cross-sectional area (CA2) located at differentlongitudinal locations along the cable, and the first cavitycross-sectional area is greater than the second cavity cross-sectionalarea.
 2. The fiber optic cable of claim 1, the cavity having a cavitycross-sectional ratio defined as the second cavity cross-sectional areadivided by the first cavity cross-sectional area, wherein the cavitycross-sectional ratio (CA2/CA1) is between 50% and 90%.
 3. The fiberoptic cable of claim 2, the at least one optical fiber having apredetermined level of coupling to the cable jacket wherein thepredetermined level of coupling is about 0.1625 Newtons or more peroptical fiber for a thirty meter length of fiber optic cable.
 4. Thefiber optic cable of claim 3, further comprising one or morewater-blocking elements disposed in the at least one cavity andcomprising one or more of a water-blocking powder, a water-blockingyarn, a water-blocking thread, a water-blocking tape, and awater-blocking gel.
 5. The fiber optic cable of claim 1, the at leastone optical fiber having a predetermined level of coupling to the cablejacket wherein the predetermined level of coupling is about 0.1625Newtons or more per optical fiber for a thirty meter length of fiberoptic cable.
 6. The fiber optic cable of claim 1, further comprising oneor more water-blocking elements disposed in the at least one cavity andcomprising one or more of a water-blocking powder, a water-blockingyarn, a water-blocking thread, a water-blocking tape, and awater-blocking gel.
 7. The fiber optic cable of claim 1, furthercomprising one or more dry inserts disposed in the at least one cavity.8. The fiber optic cable of claim 1, further comprising a first strengthelement on a first side of the at least one cavity and a second strengthelement on a second side of the at least one cavity.
 9. The fiber opticcable of claim 8, wherein at least one of the first regions has a lengthof at least 300 centimeters.
 10. The fiber optic cable of claim 9,wherein the at least one cavity is generally rectangular.
 11. The fiberoptic cable of claim 1, wherein at least one of the first regions has alength of at least 300 centimeters.
 12. A fiber optic cable comprising:at least one optical fiber; at least one dry insert; and a polymer cablejacket extruded about the at least one optical fiber, the cable jackethaving at least one cavity, wherein the at least one optical fiber andthe at least one dry insert are disposed within the at least one cavity,the cavity has a plurality of first regions having a first cavitycross-sectional area (CA1) and a plurality of second regions having asecond cavity cross-sectional area (CA2) located at differentlongitudinal locations along the cable, and the first cavitycross-sectional area is greater than the second cavity cross-sectionalarea.
 13. The fiber optic cable of claim 12, the cavity having a cavitycross-sectional ratio defined as the second cavity cross-sectional areadivided by the first cavity cross-sectional area, wherein the cavitycross-sectional ratio (CA2/CA1) is less than 90%.
 14. The fiber opticcable of claim 13, wherein the cavity cross-sectional ratio (CA2/CA1) isbetween 50% and 90%.
 15. The fiber optic cable of claim 13, the at leastone optical fiber having a predetermined level of coupling to the cablejacket wherein the predetermined level of coupling is about 0.1625Newtons or more per optical fiber for a thirty meter length of fiberoptic cable.
 16. The fiber optic cable of claim 13, further comprisingone or more water-blocking elements disposed in the at least one cavity.17. The fiber optic cable of claim 13, the at least one dry inserthaving a compressible layer and a water-swellable layer that areattached together.
 18. The fiber optic cable of claim 13, furthercomprising a first strength element on a first side of the at least onecavity and a second strength element on a second side of the at leastone cavity.
 19. The fiber optic cable of claim 18, wherein the at leastone cavity is generally rectangular.
 20. The fiber optic cable of claim19, wherein at least one of the first regions has a length of at least300 centimeters.
 21. The fiber optic cable of claim 13, wherein at leastone of the first regions has a length of at least 300 centimeters. 22.The fiber optic cable of claim 21, wherein the at least one dry insertextends through the plurality of second regions.
 23. A method formanufacturing a fiber optic cable comprising at least one optical fiberdisposed in at least one cavity of a cable jacket, comprising: providingat least one optical fiber; and extruding a cable jacket about the atleast one optical fiber, the cable jacket having a cavity, whereinextruding the cable jacket includes changing a cavity cross-sectionalarea between at least one first location and at least one secondlocation along a length of the cable jacket for improving coupling ofthe at least one optical fiber.
 24. The method of claim 23, wherein theat least one first location comprises a plurality of first locations offirst cavity cross-sectional area (CA1) and the at least one secondlocation comprises a plurality of second locations of second cavitycross-sectional area (CA2).
 25. The method of claim 24, wherein thecavity cross-sectional ratio (CA2/CA1) is less than 90%.
 26. The methodof claim 25, wherein the cavity cross-sectional ratio (CA2/CA1) isbetween 50% and 90%.
 27. The method of claim 24, wherein changing of thecavity cross-sectional area comprises extruding a cable jacket having awall thickness that varies the cavity cross-sectional area at one ormore locations along the cable jacket or deforming the cable jacketwhile is it still molten.
 28. The method of claim 24, wherein the atleast one optical fiber has a predetermined level of coupling to thecable jacket wherein the predetermined level of coupling is about 0.1625Newtons or more per optical fiber for a thirty meter length of fiberoptic cable.
 29. The method of claim 24, further comprising providingone or more water-blocking elements for inhibiting the migration ofwater along the fiber optic cable.
 30. The method of claim 24, furthercomprising applying one or more dry inserts that are disposed within theat least one cavity.
 31. The method of claim 24, further comprisingapplying a first strength element on a first side of the at least onecavity and a second strength element on a second side of the at leastone cavity.
 32. The method of claim 24, wherein an amount of polymerprovided during extrusion of the cable jacket is varied during extrusionto form the differing first and second cross-sectional areas.
 33. Themethod of claim 24, wherein during extrusion of the cable jacket adeforming element contacts the cable jacket to change the cavitycross-sectional area.
 34. The method of claim 23, wherein an amount ofpolymer provided during extrusion of the cable jacket is varied duringextrusion to form the differing first and second cross-sectional areas.35. The method of claim 23, wherein during extrusion of the cable jacketa deforming element contacts the cable jacket to change the cavitycross-sectional area.